Shock absorbing expanded adhesive and articles therefrom

Abstract

Adhesive formulations comprising expandable microspheres are described. After forming into a layer or region and expanding, the expanded adhesive layer exhibits excellent impact absorbing characteristics. The expanded adhesive layer also exhibits excellent vibration damping properties.

1 . An adhesive formulation comprising:
 50 to 99% adhesive component;   0 to 3% crosslinker;   0 to 3% antioxidant; and   0.1 to 10% expandable microspheres dispersed throughout the formulation.   
     
     
         2 . The adhesive formulation of  claim 1  further comprising from 0.1 to 30% of at least one agent selected from the group consisting of fillers, pigments, plasticizers, flame retardants, UV stabilizers, and combinations thereof. 
     
     
         3 . The adhesive formulation of  claim 1  further comprising from 0.1 to 40% tackifier. 
     
     
         4 . The adhesive formulation of  claim 1  wherein the microspheres include thermoplastic polymeric shells encapsulating gas filled hollow interior cores. 
     
     
         5 . The adhesive formulation of  claim 1  wherein the microspheres have a size prior to expansion within a range of from 5 μm to 75 μm. 
     
     
         6 . The adhesive formulation of  claim 1  wherein the microspheres expand upon exposure to a temperature within a range of from 70° C. to 220° C. 
     
     
         7 . The adhesive formulation  claim 1  wherein the microspheres exhibit a nonrupture temperature within a range of from 120° C. to 210° C. 
     
     
         8 . The adhesive formulation of  claim 1  wherein the microspheres are in an unexpanded state. 
     
     
         9 . The adhesive formulation of  claim 1  wherein the microspheres are in an expanded state. 
     
     
         10 . The adhesive formulation of  claim 9  wherein the microspheres have a size after expansion within a range of from 10 μm to 200 μm. 
     
     
         11 . The adhesive formulation of  claim 1  comprising:
 65 to 75% of the adhesive component; 
 25 to 35% of the tackifier; 
 0.1 to 1% of the crosslinker; 
 0.25 to 1% of the antioxidant; and 
 1.5 to 4% of the microspheres. 
 
     
     
         12 . A layered adhesive assembly comprising:
 a film; and   a layer of adhesive disposed on the film, the adhesive including 50 to 99% adhesive component, 0 to 3% crosslinker, 0 to 3% antioxidant, and 0.1 to 10% expandable microspheres dispersed throughout the formulation.   
     
     
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         27 . A method of absorbing mechanical shocks to a component affixed to a substrate, the method comprising:
 providing a layer of adhesive including 50 to 99% adhesive component, 0 to 3% crosslinker, 0 to 3% antioxidant, and 0.1 to 10% expandable microspheres dispersed throughout the formulation;   disposing the layer of the adhesive between the component and the substrate.   
     
     
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         31 . A layered adhesive assembly comprising:
 a first and second skin layer of adhesive,   a core layer of adhesive, the adhesive including 50 to 99% adhesive component, 0 to 5% crosslinker, 0 to 3% antioxidant, and 0.1 to 10% expandable microspheres dispersed throughout the formulation.   
     
     
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